%MNHF_CCT_SCRIPT solves for the currents in a four-loop electrical circuit. 
% The problem is lumped and steady; currents can be determined by solving 
% a 4x4 system of (linear) algebraic equations.

% Parameter input (voltages in volts, resistances in Ohms).
V1 = 60.0;
V2 = 110.0;
V3 = 200.0;
V4 = 60.0;
R1 = 22.0;
R2 = 9.0;
R3 = 10.0;
R4 = 32.0;
R5 = 41.0;
% End of parameter input.

A = [R1 -R1 0.0 0.0; -R1 R1+R2+R3 0.0 -R3; 0.0 0.0 R4+R5 -R5; ...
   0.0 -R3 -R5 R3+R5];
V = [V1; V2; V3; V4];
i = A\V;  % MATLAB's \ operator is an efficient way of solving matrix eqns.

% Print results.
fprintf('i1 (Amps) = %4.2f, i2 (Amps) = %4.2f\n',i(1),i(2))
fprintf('i3 (Amps) = %4.2f, i4 (Amps) = %4.2f\n',i(3),i(4))